TFX vs SFX PC Power Supplies: Which Should You Buy?
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You are comparing a TFX vs SFX PC power supply to find the right fit for your small form factor build. Both units are designed for compact cases, but they differ in size and capabilities. The BackPlanePro offers a standard TFX footprint with basic output, while the SilverStone provides a smaller SFX profile with higher wattage and efficiency. Your choice depends on whether you prioritize raw power and efficiency or strict compatibility with older slimline chassis designs.
Key differences
| Aspect | BackPlanePro 300W TFX Power Supply | SilverStone 700W SFX 80 Plus Gold Power Supply |
|---|---|---|
| Form Factor | TFX | SFX |
| Wattage | 300W | 700W |
| Efficiency Rating | not listed | 80 PLUS Gold |
| Modularity | not listed | Fully Modular |
| Fan Size | 80mm | 92mm |
| Dimensions | 2.56 x 3.35 x 6.89 inches | 3.94 x 2.5 x 4.92 inches |
Which one should you choose?
Choose BackPlanePro 300W TFX Power Supply if
- You need a replacement for a Dell Inspiron SFF system that requires a TFX mount.
- Your case specifically supports the larger TFX form factor dimensions.
- You are building a low-power system that only requires 300W of output.
Choose SilverStone 700W SFX 80 Plus Gold Power Supply if
- You require high efficiency and lower heat output with an 80 PLUS Gold rating.
- You want flexible cable management with fully modular connectors.
- Your compact case supports the SFX form factor and you need up to 700W of power.
Verdict: Choose the BackPlanePro if you are replacing a specific legacy slimline unit that mandates the TFX form factor. Select the SilverStone if you are building a modern small form factor PC that requires higher efficiency, modularity, and greater wattage. The SFX unit offers more versatility for new builds, while the TFX is a niche replacement part.
TFX vs SFX PSU Comparison
Form Factor Size
The BackPlanePro follows the standard TFX footprint, measuring 6.89 inches in length, 3.35 inches in height, and 2.56 inches in width. This is the traditional dimension for TFX cases. The SilverStone unit is an SFX model with different dimensions: 4.92 inches long, 2.5 inches high, and 3.94 inches wide. While both fit small form factor cases, they are not interchangeable. You must check your case specifications to see if it accepts TFX or SFX mounts. The mounting hole patterns differ between these two standards.
Wattage Output
Power delivery capabilities vary significantly between these units. The BackPlanePro provides 300W of total power. This output is suitable for basic office systems or low-power builds with integrated graphics. The SilverStone offers 700W of power. This higher capacity supports more demanding components, such as dedicated graphics cards and high-performance processors. If your build requires substantial power for gaming or heavy workloads, the SilverStone provides the necessary headroom. The BackPlanePro is limited to lighter tasks due to its lower wattage rating.
Efficiency Rating
Energy efficiency impacts your electricity costs and system heat output. The SilverStone holds an 80 PLUS Gold certification. This rating indicates high efficiency, meaning less energy is lost as heat during conversion. The BackPlanePro data does not list an official efficiency certification. It features active PFC, which helps with power factor correction, but this is not the same as an 80 PLUS rating. For users concerned about power waste and thermal output in a small case, the certified efficiency of the SilverStone is a clear technical advantage.
Modularity
Cable management is critical in small form factor builds to maintain airflow. The SilverStone is fully modular, allowing you to connect only the cables you need. It includes flexible flat arrays for easier routing in tight spaces. The BackPlanePro data does not specify modularity, implying it is likely a fixed-cable unit. Fixed cables can clutter a small case and obstruct airflow. The ability to remove unused cables with the SilverStone simplifies installation and improves cooling efficiency inside compact chassis.
Voltage Regulation
Stable power delivery protects your components from damage. The SilverStone specifies strict 3% voltage regulation and low ripple and noise. This precision ensures consistent power to sensitive electronics. The BackPlanePro description mentions robust and reliable output but does not provide specific voltage regulation percentages or ripple noise levels. Without these technical details, it is harder to verify the stability of the power delivery. The explicit regulation specs of the SilverStone offer greater assurance for high-performance systems.
Choose your TFX or SFX PSU
Users needing a direct Dell Inspiron replacement
This BackPlanePro unit is explicitly designed to support and replace Dell Inspiron 530s and 531s SFF systems. If your case requires a specific TFX footprint and you need a 300W output with an 80mm fan, this model provides the robust and reliable output required for your entire system without compatibility issues.
Builders requiring high efficiency and low noise
The SilverStone unit features 80 PLUS Gold certification for high efficiency and a silent 92mm FDB fan with 18 dBA minimum noise. It offers a class-leading single +12V rail with strict 3% voltage regulation. This combination ensures peak performance and quiet operation for demanding builds in compact SFX cases.
Enthusiasts wanting fully modular cable management
This SilverStone power supply is fully modular with 100% flexible flat array cables. This feature simplifies cable management in tight SFX builds. With 700W of power and Japanese capacitors, it supports high-end components while maintaining clean aesthetics and efficient power delivery for your compact computer setup.
Quick picks
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | BackPlanePro 300W TFX Power Supply | Dell Inspiron SFF replacement builds | Check price of BackPlanePro 300W TFX Power Supply on Amazon |
| 2 | SilverStone 700W SFX 80 Plus Gold Power Supply | High-power SFX builds | Check price of SilverStone 700W SFX 80 Plus Gold Power Supply on Amazon |
The products compared
BackPlanePro 300W TFX Power Supply
Best for: Dell Inspiron SFF replacement builds
- Form Factor
- TFX (what this guide is about)
- Wattage
- 300W
- Fan Size
- 80mm
- Warranty
- One Year
- Dimensions
- 6.89 × 2.56 × 3.35 inches
- Weight
- 3 pounds
View on Amazon: BackPlanePro 300W TFX Power Supply Affiliate link
This BackPlanePro unit is a 300W TFX power supply designed for small form factor builds. It features an 80mm silent fan and active PFC. The grey unit measures 6.89 by 3.35 by 2.56 inches. It weighs 3 pounds. You should choose this if you need a direct replacement for Dell Inspiron SFF systems. It offers reliable output for low-power microATX cases.
Pros
- 300W wattage output
- 80mm silent cooling fan
- Active PFC with auto switch
- TFX form factor for slim cases
Cons
- 300W limit is low for modern high-end PCs
- One-year warranty is shorter than typical standards
- Not 80 Plus certified for efficiency
Good fit if
- You are replacing a Dell Inspiron 530s or 531s power supply
- You build a low-power microATX system
- You need a compact TFX unit under 300W
Skip if
- You need more than 300W of power
- You require 80 Plus Gold efficiency ratings
- You want a longer warranty than one year
Verdict: BackPlanePro 300W TFX Power Supply is a niche replacement for specific Dell SFF systems. It suits users with low-power microATX builds who need exact form factor compatibility.
SilverStone 700W SFX 80 Plus Gold Power Supply
Best for: High-power SFX builds
- Form Factor
- SFX (what this guide is about)
- Wattage
- 700W
- Efficiency Rating
- 80 PLUS Gold
- Modularity
- Fully Modular
- Fan Size
- 92mm
- Dimensions
- 4.92 × 3.94 × 2.5 inches
View on Amazon: SilverStone 700W SFX 80 Plus Gold Power Supply Affiliate link
This SilverStone unit is a 700W SFX power supply designed for small form factor builds. It features 80 PLUS Gold efficiency and a fully modular cable design. The 92mm fan ensures quiet operation at just 18 dBA. It delivers a stable single +12V rail with strict voltage regulation. This PSU suits users needing high power in a compact SFX chassis.
Pros
- 700W output capacity
- 80 PLUS Gold efficiency rating
- Fully modular cable design
- Quiet 92mm FDB fan
Cons
- SFX form factor limits ATX compatibility
- 92mm fan may spin louder under heavy load
- Heavier than standard SFX units at 3.09 pounds
Good fit if
- You need 700W in a small case
- You want high efficiency for lower heat
- You prefer modular cable management
Skip if
- Your case only supports ATX PSUs
- You need more than 700W power
- You require a silent 120mm fan
Verdict: SilverStone 700W SFX Gold PSU offers solid power density and efficiency for compact builds. It fits users who prioritize high wattage and quiet operation in small form factor cases.
Specifications side by side
| Spec | BackPlanePro 300W TFX Power Supply | SilverStone 700W SFX 80 Plus Gold Power Supply |
|---|---|---|
| Wattage | 300W | 700W |
| Efficiency Rating | not stated | 80 PLUS Gold |
| Modularity | not stated | Fully Modular |
| Fan Size | 80mm | 92mm |
| Warranty | One Year | not stated |
| Form Factor | TFX | SFX |
| Dimensions | 6.89 × 2.56 × 3.35 inches | 4.92 × 3.94 × 2.5 inches |
| Weight | 3 pounds | 3.09 pounds |
| Color | Grey | Black?Lead-Free Paint? |
| Model | LYSB00CXAUQJK-CMPTRACCS | SST-SX700-G |
| Size | not stated | 700W |
Frequently asked questions
Can I use an SFX power supply in a TFX case?
No, you cannot directly install an SFX unit in a TFX case. The SFX form factor is physically larger than TFX. For example, the SilverStone SFX model measures 4.92 inches in length, while TFX units like the BackPlanePro are significantly longer at 6.89 inches. You must match the PSU form factor to your case specifications to ensure proper fit.
Which form factor supports higher wattage?
SFX power supplies generally support higher wattage than TFX units. The SilverStone SFX model offers 700W of power output, which is ideal for high-performance builds. In contrast, the BackPlanePro TFX unit provides only 300W. If you need substantial power for graphics cards or multiple drives, the SFX form factor is the better choice for your compact build.
Are SFX power supplies fully modular?
Some SFX models are fully modular, while others are not. The SilverStone 700W SFX unit features fully modular cabling, allowing you to connect only the cables you need. This reduces clutter in small cases. The BackPlanePro TFX unit does not list modularity in its specifications, suggesting it may be non-modular. Check the specific product details to confirm.
What is the weight difference between TFX and SFX PSUs?
The weight varies by model rather than form factor alone. The BackPlanePro TFX unit weighs 3 pounds. The SilverStone SFX unit weighs 3.09 pounds. These weights are comparable. You should consider the total weight when building in tight spaces. Both units are relatively light, making them suitable for portable or small form factor chassis.
Is 80 Plus Gold efficiency common in TFX power supplies?
High efficiency ratings like 80 Plus Gold are more common in SFX units. The SilverStone SFX model carries an 80 Plus Gold rating for better energy efficiency. The BackPlanePro TFX unit does not list an efficiency rating in its data. If energy savings and cooler operation are priorities, an SFX model with a Gold certification is likely a better fit.
Who should buy a TFX power supply?
You should buy a TFX power supply if you are replacing a unit in a specific Dell Inspiron SFF system. The BackPlanePro 300W TFX unit is designed for this niche replacement. It is also suitable for low-power microATX builds that require the smaller TFX footprint. If you need a direct drop-in replacement for older Dell hardware, TFX is the correct choice.